My amps clipping??!!

[Jamesemt]

Never had any problems with my Fender P through a Superfly and Eden cabs until last night - I changed basses (to a Jazz) and couldn't stop the amp clipping.

Now I realise that my technique isn't great but I turned the compressor up full and it made little difference. I kept turning the input signal down so that with regular playing the green LEDs were at about a 1/3rd but was still managing to get the amp to clip on occasion (maybe gettig a bit carried away...). I think the problem stems from me normally playing relatively quietly (err until a big chorus??!!) - is it more of a technique issue?

Do I need a limiter?

Is this thread even in the right place??

[cheddatom]

If the clipping is caused by peaks in your playing, yes a limiter will help! The compressor probably doesn't help that much because it wont compress the attack - often the loudest portion of your notes.

[1976fenderhead]

[quote name='cheddatom' post='284791' date='Sep 16 2008, 09:50 AM']If the clipping is caused by peaks in your playing, yes a limiter will help! The compressor probably doesn't help that much because it wont compress the attack - often the loudest portion of your notes.[/quote]

er... since when doesn't a compressor compress the attack? That's kind of half of all it does...

[cheddatom]

[quote name='1976fenderhead' post='284811' date='Sep 16 2008, 10:27 AM']er... since when doesn't a compressor compress the attack? That's kind of half of all it does...[/quote]

A compressor will compress the attack if you set the attack time to 0 seconds - but then you might as well call it a limiter without the infinite ratio. The attack control on a compressor sets how quickly the compression kicks in, so if you have a slow attack time, or anything other than 0ms the first portion of the note will not be compressed.

Unless again I am talking out of my arse? I thought I knew about this kind of stuff but maybe not?

[1976fenderhead]

[quote name='cheddatom' post='284816' date='Sep 16 2008, 10:34 AM']A compressor will compress the attack if you set the attack time to 0 seconds - but then you might as well call it a limiter without the infinite ratio. The attack control on a compressor sets how quickly the compression kicks in, so if you have a slow attack time, or anything other than 0ms the first portion of the note will not be compressed.

Unless again I am talking out of my arse? I thought I knew about this kind of stuff but maybe not?[/quote]

yes, that's correct, but since in principle the attack is the loudest portion of a note, and a compressor, in principle, makes loud bits quieter and quiet bits louder, you will always be affecting attack to a certain degree, unless if you just want to bring the quiet bits up, which wouldn't be the case here.

The way I see it, a compressor can do for the loud bits the same a limiter does, plus a compressor can enhance quiet bits and a limiter can't.

Edited September 16, 2008 by 1976fenderhead

[cheddatom]

The reason I said this was because his amp is clipping, so the loudest peaks are affecting his amp. If he wants to reduce those peaks he would do better to get a limiter, an/or a compressor set to 0ms attack and infinite ratio. The he can set the threshold so than only the loudest peaks are limited, and it will stop the amp clipping. If he uses a compressor with a slower attack than 0 to do the same thing, then the attack portion of the note will always come through and will always be the loudest, and the "peakiest" and wont stop the amp clipping at these points.

This "a compressor, in principle, makes loud bits quieter and quiet bits louder" is not neccessarily true when you correspond the dynamic response to time. Yes, you can use a compressor to make loud bits quieter and quiet bits louder, but the attack part of the note will still be avoiding any compression, and wont be made any quieter. If the compression is so great that the rest of the note is brought up to the same level as that of the attack part (i'd say it'd sound awful!) then the amp would constantly be clipping, although seeing as his perceived level will be louder, he can turn down the amp and it shouldn't clip.

So basically, although your post makes sense, I think that a limiter could solve his problem, where a compressor wont.

[1976fenderhead]

[quote name='cheddatom' post='284871' date='Sep 16 2008, 11:34 AM']The reason I said this was because his amp is clipping, so the loudest peaks are affecting his amp. If he wants to reduce those peaks he would do better to get a limiter, an/or a compressor set to 0ms attack and infinite ratio. The he can set the threshold so than only the loudest peaks are limited, and it will stop the amp clipping. If he uses a compressor with a slower attack than 0 to do the same thing, then the attack portion of the note will always come through and will always be the loudest, and the "peakiest" and wont stop the amp clipping at these points.

This "a compressor, in principle, makes loud bits quieter and quiet bits louder" is not neccessarily true when you correspond the dynamic response to time. Yes, you can use a compressor to make loud bits quieter and quiet bits louder, but the attack part of the note will still be avoiding any compression, and wont be made any quieter. If the compression is so great that the rest of the note is brought up to the same level as that of the attack part (i'd say it'd sound awful!) then the amp would constantly be clipping, although seeing as his perceived level will be louder, he can turn down the amp and it shouldn't clip.

So basically, although your post makes sense, I think that a limiter could solve his problem, where a compressor wont.[/quote]

Don't we both agree that a limiter or a compressor with 0ms attack and infinite ratio would solve his problem?

[cheddatom]

[quote name='1976fenderhead' post='284877' date='Sep 16 2008, 11:40 AM']Don't we both agree that a limiter or a compressor with 0ms attack and infinite ratio would solve his problem? [/quote]

Yup

But that's not what you were saying earlier? A compressor with 0ms attack and infinite ratio = a limiter. You were saying that a compressor does compress attack, "That's kind of half of all it does". I said it doesn't, unless you set it exactly as a limiter, which would make it a limiter. There's a reason there are two different names for these things.

Not trying to make an argument, just explaining my reasons for posting

[tauzero]

[quote name='Jamesemt' post='284785' date='Sep 16 2008, 09:44 AM']Do I need a limiter?[/quote]
No, just a Superfly editor, a computer, and a USB lead...

You can set compression attack with the editor, so you could experiment with that and see if you can get it limiting the peaks a bit better.

[cheddatom]

[quote name='tauzero' post='287146' date='Sep 19 2008, 10:54 AM']No, just a Superfly editor, a computer, and a USB lead...

You can set compression attack with the editor, so you could experiment with that and see if you can get it limiting the peaks a bit better.[/quote]

Wow! That's pretty cool.

[Silent Fly]

[quote name='Jamesemt' post='284785' date='Sep 16 2008, 09:44 AM']Do I need a limiter?[/quote]

No, you don’t.

An amp should sound good without any external (or internal) processing. If it clips the problem can be in the bass, cab, bass or cables.

I suggest you try the elements of your chain one at the time to be 100% sure that nothing is faulty.

Start with the bass. Connect the bass to another amp or recording equipment to find out if the bass has any problem. It could be the onboard preamp if the bass is active or the soldering of the internal components (even for passive basses).

If you are positive that bass and cables are ok, do the following:

* Connect the bass to the amp with no effects. Just a good quality cable.
* Set your bass with no eq boost/cut.
* Set your amp as follows:
- Master volume low (1/10 or less),
- tone/eq flat,
- compressor off,
- play as hard as you can (within reason) and set the input/gain knob to the level suggested by the instruction manual.

With these settings the input stage of you amp (i.e. preamp) will not clip.

Turn up the master volume to the level you like (do [i]not[/i] touch the tone/eq/compressor settings). Play a couple of songs. It is clips it might be for three reasons:

- The amp is not powerful enough for your needs. In other words you are asking the power section of your amp to deliver more power than is capable of.
- The amp is faulty.
- The cabinet is not powerful enough for the amp (less likely).

If under the above conditions the bass/amp/cabinet never clips, the problem is in the settings.

My guess is that you boost the bass frequency controls of your amp (or/and bass) too much. Consider that for every +3dB of increment you are asking your amp to [url="http://http://www.crownaudio.com/apps_htm/designtools/db-power.htm"]double the power is delivering.[/url]

To give you a very rough idea, if you play with the master at 1/4 but you boost the bass frequencies by 6db you are actually using all the power available. Turning the master to a more than 1/4 would clip the power stage.

…or in other words, if you have a 250w amp that runs at 50% of the maximum power (flat eq) you will need roughly:

250w for supporting +3dB boost (max power for 1 ch of the Superfly)
314w for +4dB (your Superfly is already short of power) :wacko:
500w for +6dB
1000w for +9dB
2000w for +12db
4000w for +15dB

The amp compressor can help mitigate the effects of eq on the power but its behaviour depends on the positions in the amplifier design. If the compression is applied before the eq (pre-eq) or after the eq (post-eq) the result is different.

I can't find the information in the Superfly manual but I have the feeling that the compression is pre-eq. In this case, big dynamic peaks due to extreme boost of some frequencies cannot be directly controlled by the compressor. This may be the reason why you cannot avoid the clipping using the amp compressor.

I hope the above helps.

Edited September 19, 2008 by Silent Fly